A display device such as a liquid crystal display device and an organic electroluminescent display device may be provided with an optical film formed from a resin. Such an optical film is usually formed so as to have a size larger than that of a film piece which is a final product. The film is cut into a desired shape which is matched to a rectangular display face of the display device to obtain a film piece, and the obtained film piece is provided in the display device.
Examples of a method for cutting the film into a desired shape may include a mechanical cutting method using a knife and a laser cutting method using laser light. Of these methods, the laser cutting method is preferable as the method is less likely to generate cut chips.
Such a production method is used in, for example, production of a polarizing plate. In the production, a layered body having a support made of glass and a resin layer, such as a polarizer, provided on the support is prepared, and the resin layer in the layered body is cut using laser light into a desired shape which is matched to a rectangular display face of a display device. The cut resin layer is provided in the display device as a polarizing plate. The support may be removed from the polarizing plate and used again in the next production, and may also be incorporated in the display device in combination with the polarizing plate as a part of component of the display device.
The energy distribution of a beam of the laser light used in the cutting method is generally in a state which is called Gaussian mode. The beam in the Gaussian mode is in a state where the energy is high at an optical axis which is a center of the beam and the energy is low at a position apart from the optical axis. On the other hand, use of a beam having a flat energy distribution, the shape of which is called top hat profile, is also known in order to perform precise cutting (Patent Literatures 1 and 2).